export function Recorder(stream, config) {
    config = config || {};
    config.sampleBits = config.sampleBits || 16;   //采样数位 8, 16
    config.sampleRate = config.sampleRate || 16000;  //采样率16khz

    let context = new (window.webkitAudioContext || window.AudioContext)()
    let audioInput = context.createMediaStreamSource(stream)
    let audioData = null;
    const createScript = context.createScriptProcessor || context.createJavaScriptNode;
    const recorder = createScript.apply(context, [4096, 1, 1]);

    this.load = function () {
        audioData = {
            size: 0,     //录音文件长度
            buffer: [],   //录音缓存
            inputSampleRate: context.sampleRate,  //输入采样率
            inputSampleBits: 16,    //输入采样数位 8, 16
            outputSampleRate: config.sampleRate,  //输出采样率
            outputSampleBits: config.sampleBits,    //输出采样数位 8, 16
            input: function (data) {
                this.buffer.push(new Float32Array(data));
                this.size += data.length;
            },
            clear: function () {
                this.buffer = []
            },
            compress: function () { //合并压缩
                //合并
                const data = new Float32Array(this.size);
                let offset = 0;
                for (let i = 0; i < this.buffer.length; i++) {
                    data.set(this.buffer[i], offset);
                    offset += this.buffer[i].length;
                }
                //压缩
                const compression = parseInt(this.inputSampleRate / this.outputSampleRate);
                const length = data.length / compression;
                const result = new Float32Array(length);
                let index = 0, j = 0;
                while (index < length) {
                    result[index] = data[j];
                    j += compression;
                    index++;
                }
                return result;
            },
            encodeWAV: function () {
                let s;
                let i;
                const sampleRate = Math.min(this.inputSampleRate, this.outputSampleRate);
                const sampleBits = Math.min(this.inputSampleBits, this.outputSampleBits);
                const bytes = this.compress();
                const dataLength = bytes.length * (sampleBits / 8);
                const buffer = new ArrayBuffer(44 + dataLength);
                const data = new DataView(buffer);

                const channelCount = 1;//单声道
                let offset = 0;

                const writeString = function (str) {
                    for (let i = 0; i < str.length; i++) {
                        data.setUint8(offset + i, str.charCodeAt(i));
                    }
                }

                // 资源交换文件标识符
                writeString('RIFF');
                offset += 4;
                // 下个地址开始到文件尾总字节数,即文件大小-8
                data.setUint32(offset, 36 + dataLength, true);
                offset += 4;
                // WAV文件标志
                writeString('WAVE');
                offset += 4;
                // 波形格式标志
                writeString('fmt ');
                offset += 4;
                // 过滤字节,一般为 0x10 = 16
                data.setUint32(offset, 16, true);
                offset += 4;
                // 格式类别 (PCM形式采样数据)
                data.setUint16(offset, 1, true);
                offset += 2;
                // 通道数
                data.setUint16(offset, channelCount, true);
                offset += 2;
                // 采样率,每秒样本数,表示每个通道的播放速度
                data.setUint32(offset, sampleRate, true);
                offset += 4;
                // 波形数据传输率 (每秒平均字节数) 单声道×每秒数据位数×每样本数据位/8
                data.setUint32(offset, channelCount * sampleRate * (sampleBits / 8), true);
                offset += 4;
                // 快数据调整数 采样一次占用字节数 单声道×每样本的数据位数/8
                data.setUint16(offset, channelCount * (sampleBits / 8), true);
                offset += 2;
                // 每样本数据位数
                data.setUint16(offset, sampleBits, true);
                offset += 2;
                // 数据标识符
                writeString('data');
                offset += 4;
                // 采样数据总数,即数据总大小-44
                data.setUint32(offset, dataLength, true);
                offset += 4;
                // 写入采样数据
                if (sampleBits === 8) {
                    for (i = 0; i < bytes.length; i++, offset++) {
                        s = Math.max(-1, Math.min(1, bytes[i]));
                        let val = s < 0 ? s * 0x8000 : s * 0x7FFF;
                        val = parseInt(255 / (65535 / (val + 32768)));
                        data.setInt8(offset, val, true);
                    }
                } else {
                    for (i = 0; i < bytes.length; i++, offset += 2) {
                        s = Math.max(-1, Math.min(1, bytes[i]));
                        data.setInt16(offset, s < 0 ? s * 0x8000 : s * 0x7FFF, true);
                    }
                }

                return new Blob([data], {type: 'audio/wav'});
            },
        };
    }

    this.reload = function () {
        audioData.clear()
    }

    //开始录音
    this.start = function () {
        audioInput.connect(recorder);
        recorder.connect(context.destination);
    }

    //停止
    this.stop = function () {
        recorder.disconnect();
    }

    //获取音频文件
    this.getBlob = function () {
        //this.stop();
        return audioData.encodeWAV();
    }

    //回放
    this.play = function (audio) {
        const blob = this.getBlob();
        // saveAs(blob, "F:/3.wav");
        audio.src = window.URL.createObjectURL(this.getBlob());
    }

    //上传
    this.upload = function () {
        return this.getBlob()
    }

    //音频采集
    recorder.onaudioprocess = function (e) {
        audioData.input(e.inputBuffer.getChannelData(0));
        //record(e.inputBuffer.getChannelData(0));
    }

}